title: RecQ5 protein translocation into the nucleus by a nuclear localization signal.
abstract: RecQ5, a member of the RecQ helicase family, maintains genome stability via participation in many DNA metabolic processes including DNA repair, DNA resolution, and RNA transcription, processes occurring in the nucleus. Previously, we reported that RecQ5 and Rad51, also involved in DNA repair, become co-localized in nuclei when co-expressed in cultured cells. Nuclear localization of RecQ5 appears to be important for cellular function along with Rad51. However, little is known about the nuclear localization of RecQ5. Here, we generated enhanced green fluorescent protein (EGFP)-tagged RecQ5 transgenic flies and analyzed localization of this protein in early embryos by live imaging. In syncytial embryos, RecQ5 was localized synchronously in interphase nuclei, and spread repeatedly over the embryos in mitosis. Thus, RecQ5 was transported into nuclei at the early interphase. Furthermore, we examined the subcellular localization of a series of truncated forms of Drosophila RecQ5 in cultured cells to determine the nuclear localization signal (NLS). Entire coding or deleted RecQ5 sequences of various sizes were ligated into EGFP vectors, which were then used to transfect cultured Drosophila cells. The region responsible for nuclear localization of Drosophila RecQ5 contained a short stretch of positively charged basic amino acids, 2 of which were particularly important for the nuclear localization. This stretch was sufficient for nuclear localization when fused with EGFP. Although the NLS of Drosophila RecQ5 was distinct from that of human RECQL5 in terms of position and amino acid sequence, this fly RecQ5 protein was translocated into the nucleus by an NLS.
authors.affiliation: Division of Biochemistry, Graduate School of Pharmaceutical Sciences, Setsunan University, Osaka 573–0101, Japan.
authors.forename: Haruna
authors.initials: H
authors.lastname: Sakurai
authors.forename: Ayaka
authors.initials: A
authors.lastname: Tsutsui
authors.forename: Takahiro
authors.initials: T
authors.lastname: Higashi
authors.forename: Rika
authors.initials: R
authors.lastname: Azuma
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Ito
authors.forename: Katsumi
authors.initials: K
authors.lastname: Kawasaki
mesh_terms: D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D004265:DNA Helicases; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology / Q000201:enzymology; D049452:Green Fluorescent Proteins / Q000235:genetics; D007399:Interphase / Q000502:physiology; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals / Q000502:physiology*; D010957:Plasmids; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism; D053484:RecQ Helicases / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D029721:Drosophila Proteins; D019913:Nuclear Localization Signals; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D051135:Rad51 Recombinase; D004265:DNA Helicases; D053484:RecQ Helicases; C407462:RecQ5 protein, Drosophila